// let num = 123
// let str = 'hello'
// let flag = true
// let un = undefined
// let nu = null


// let obj = {}
// let fn = function () {}
// let arr = []
// let date = new Date()


// let a = 1
// let b = a
// a = 2
// console.log(b);


let a = {
  age: 18
}
let b = a
a.age = 20
console.log(b.age);